That's easy! Just click on the model and uncheck "Available to all".
You can recognize if the models are available in your shop when the shopping cart logo at the left bottom is pink. If it is grey than it is not available in your shop.
Ive done that but I was hoping there would be a way to complelty delete it from the system. When Im viewing my own shop and trying to keep track of things, things get very cluttered with unwanted models.
underneath your viewing window there are 3 buttons 'enlarge' 'view in 3d' and 'delete'... delete makes your model disappear completely from the system from what I can tell